Allergen Exposure

Geographical distributionThe Common Red Fox is found in Eurasia, North Africa, and North America. Foxes live almost throughout the world, but are particularly numerous in the Northern Hemisphere. They are known for their raids on poultry but are nonetheless very beneficial to farmers as destroyers of rodents. Despite extensive killing of Foxes-for sport, for their fur, and to reduce predation of livestock-most species continue to flourish, as they are semi-omnivorous, intelligent and adaptable. Foxes are also bred in captivity for their fur.

The Fox has a pointed face, short legs, long, thick fur, and a tail about one half to two thirds as long as the head and body, depending on the species. Colours vary widely, but as the name suggests, in Red Foxes reddish colours predominate.

EnvironmentFoxes usually inhabit areas of forest mixed with open country, in many kinds of climate. Although most active at night, they are also seen by day.

AllergensUrine extracts of Blue Fox and Silver Fox contained more protein bands than the fur extracts did. Allergenic bands of 62-67 kDa, 23-25 kDa and 18-19 kDa have been detected in fur and urine extracts, but the allergens have yet to be characterised (1).

Potential Cross-Reactivity

Allergens with the same molecular weight were found in Mink, Blue Fox, Silver Fox, Raccoon, Dog and Fitchew fur and urine extracts. With cross-reacting sera the reciprocal RAST inhibition with all 5 animal extracts indicated common IgE-binding epitopes, probably common allergens (especially the 62-67 kDa bands). Urine and fur contain common allergens, since urine allergens strongly inhibited IgE binding to fur allergens. The IgE binding to allergenic bands of fur animal (Fox, Mink, Raccoon) extracts was also observed in immunoblotting when Dog and Cat Specific IgE containing sera were used. RAST inhibition of Dog-positive sera with fur animal extracts and fur-animal-positive sera with Dog extract confirmed the cross-reactivity of these IgE antibodies. No such inhibition was seen with Cow extract. These results suggest that fur animals have IgE binding epitopes or allergens-possibly albumin-in common with Cat and Dog; but not with Cow (1).

Clinical Experience

IgE mediated reactionsAsthma, allergic rhinitis and allergic conjunctivitis may result from occupational exposure to Fox epithelium, and may occur in hunters (1, 2).

In 42 women occupationally exposed in the fur manufacturing industry, the highest prevalence of positive immediate skin reactions to antigen of animal hair was found for marten (10%), followed by Fox and lamb (7%), mink (5%), and Chinese lamb, domestic Fox, and Chinese calf (2%). Precipitating antibodies were demonstrated for lamb (17%), astrakhan (14%), mink, domestic Fox and skunk (12%), Chinese lamb (10%), and Chinese calf (7%). Increased total IgE was found in 9.5% of subjects. A high prevalence of acute symptoms during the work shift was found among furriers. In general, greater drops in respiratory parameters occurred in individuals with positive precipitins as opposed to those with positive skin tests. This study suggests that workers in the fur manufacturing industry develop acute and chronic respiratory problems often associated with specific indicators of atopy (2).

One hundred and eighty-eight fur farmers and fur garment workers and a control group were given a self-administered questionnaire, lung function tests, and skin-specific IgE tests to common environmental allergens, and epithelium and urine of fur animals. Symptoms of rhinitis and conjunctivitis were significantly more common among the fur garment workers than among the control group, but were not associated with atopy (3).